Fig. 4

Longitudinal characterization of spontaneous network activity in organotypic hippocampal cultures from neonatal Gad-Grik1^−/− mice. A Example traces of the extracellular recordings across hippocampal regions in control and Gad-Grik1^−/− cultures at DIV5. The inserts show typical bursts with the CA1/CA3–DG phase shift. Red arrowheads mark network bursts. B Frequency of spikes detected in the CA1 (i), CA3 (ii) and DG (iii) regions of control (n = 12 (6)) and Gad-Grik1^−/− cultures (n = 9 (6)). Both genotypes show equal spike rates in the CA1 and DG regions, but the frequency of spikes in area CA3 is lower in the Gad-Grik1^−/− as compared to controls (p = 0.0001, 2-way ANOVA). C Frequency of spontaneous bursts in the CA1, CA3, DG regions of control (n = 11(6)) and Gad-Grik1^−/− slices (n = 9 (6)) at indicated DIV (p < 0.05, 2-way ANOVA). D Duration of spontaneous bursts in CA1, CA3, DG regions of control (n = 11(6)) and Gad-Grik1^−/− (n = 9(6)) slices at indicated DIV  (p < 0.01, 2-way ANOVA). E Image of the hippocampal organotypic culture on MEA probe (left) and example heat maps showing the spread of network activity following a spike in the DG, in control and Gad-Grik1^−/− cultures at 5 DIV. F Time course plot illustrating the mean number of spatially adjacent MEA channels (out of total 64) displaying activity during a 100 ms time period after a DG spike in control (n = 10(6)) and Gad-Grik1^−/− (n = 9(6)) cultures. The dashed blue line denotes the time point of DG spike. G Pooled data on the maximum number of spatially adjacent active channels during the first 20 ms following a DG spike (*p < 0.05, Mann–Whitney U-test). H The same data as in F, normalized to the first 4 time bins (20 ms) following the spike. (** p < 0.01, 2-way ANOVA). I Normalized number of spatially adjacent active channels 30–70 ms after the DG spike (****p < 0.0001, Mann–Whitney U-test.). Bars represent mean ± SEM. The n-values refer to number of cultures, followed by number of animals in parenthesis